Welcome to Nikonians! When Canon introduced their new EOS line of autofocus cameras in 1988 they did something that no other maufacturer had done. They totally abandoned their previous lenses. The FD mount lenses used on their manual focus cameras simply would not fit on the new EOS cameras at all. Not only was the mount coupling different, but the "flange to focal plane" distance was longer (44mm vs 42mm), so even if an adapter was made which allowed an FD lens to mecanically couple to the EOS mount, the lens wouldn't focus to infinity. To allow the lens to focus to infinity, the flange of the FD lens would have to be 2mm inside the EOS body. So her Canon lenses will not work on an EOS Digital Rebel T1i.